Created attachment 270642 [details]
Testcase demonstrating the problem
Steps to reproduce:
1. Open the attached testcase in iOS Safari.
2. Tap the "Launch demo modal" button.
3. Tap into the 2nd text field.
4. Type some text.
5. Tap the Done button.
6. Perform a scroll-down gesture (i.e. flick your finger upward), but start the scroll gesture within the bounds of the 2nd text field.
The <body> scrolls downward.
The yellow <div> (which is a descendant of a position:fixed <div>) should scroll downward.
The <body> shouldn't scroll at all, because it's styled as overflow:hidden.
Original Bootstrap bug: https://github.com/twbs/bootstrap/issues/14839#issuecomment-60940738
This is similar to bug 153852, but that bug usually occurs only when the position:fixed element has already been scrolled to its top or bottom,
whereas this bug doesn't have that requirement and seems to be related to text fields specifically.
Created attachment 270643 [details]
GIF video demonstrating the bug